Infrared devices are used in many practical applications, such as communications, security systems and other modern electronic devices. One of these infrared devices is disclosed in U.S. Pat. No. 5,013,918 entitled "Multicolor Infrared Photodetector" issuing to Choi on May 7, 1991, which is herein incorporated by reference. Yet another infrared device is disclosed in the article "10 .mu.M infrared hot-electron transistors", Applied Physics Letters, Vol. 57(1990) pg. 1348-1350.
Many of the infrared detection devices use a photoconductor or photodiode to detect infrared radiation. While photoconductors work in many applications, the desired signal is often relatively low or limited in amplitude. Additionally, it is difficult to directly connect a photoconductor to a high gain amplifier. The typical application of a photoconductor in infrared detection requires a biasing voltage to be applied on the photoconductor. This applied bias prevents the photo signal from being directly coupled to a high gain amplifier, since the applied bias will saturate the amplifier output. The usual technique for using a photoconductor in light detection is the modulation of light intensity using a light chopper and AC coupling of the photo signal to the high gain amplifier. However, this results in a relatively complicated electrical system.
Therefore, there is a need for an electrical circuit that will be relatively simple and provide a more desirable output signal upon detection of infrared radiation.